The present invention relates to the field of robotic end effectors and more particularly to end effectors suitable for the manipulation of articles such as mail.
The high volume of mail which is handled by the U.S. Postal Service makes it desirable to sort mail in a fully automatic manner. One category of mail which presents particular problems for sorting is known as flats. Flats include relatively wide, relatively thin envelopes and magazines whose lateral dimensions range from 6.0 to 11.12 inches by 7.5 to 15.0 inches and whose thickness varies from a single sheet of paper to as thick as one inch or more. Incoming flats arrive at a sorting center in bags or bins and are dumped into the sorting system. As a result, there is no predetermined orientation or order to those flats. In addition, the location of the flat which is on top of the pile of flats is not predictable. In order to sort these flats, each one must be removed from the incoming pile, have its destination determined and then be placed in an appropriate outgoing bin or conveyor.
The sorting of such articles creates particular problems for robotic systems because of the varying sizes of the flats, their varying orientations and the inclusion in flats of envelopes which are sealed at all sides, magazines which are enclosed in sleeves and magazines which are bound along only one edge and not enclosed in sleeves. To be effective, a robotic system for sorting such flats must be small, reliable, capable of high-speed operation and able to handle the full variety of flats in whatever orientation they arrive at the robotic system. Thus, there is a need for a robotic end effector which can manipulate flats in a variety of sizes and configurations including sealed envelopes, bound magazines in sleeves and bound magazines without sleeves.